Development Guidelines

[Writing Requirements]

Mandatory. Describe how a developer completes tasks in a specific scenario. Include one scenario in each section. The table below describes the writing requirements. After finishing the writing, check your content against these requirements one by one.

When to Use

[Writing Requirements]

Mandatory. Describe in which scenario, what problem is solved, and what the final effect is. Use the SCQA method.

• S: situation. Introduce a familiar scenario.

• C: complication. Describe the conflict between the situation and requirement.

• Q: question. Ask a question. What can I do in such a case?

• A: answer. Describe the solution.

The table below describes the writing requirements. After finishing the writing, check your content against these requirements one by one.

[Example]

You can use APIs described in this section to convert audio data into audible analog signals, play the audio signals using output devices, and manage playback tasks.

Available APIs

[Writing Requirements]

Mandatory. Describe APIs involved in the development guideline to help developers have a general understanding of the APIs, thereby improving development efficiency. The table below describes the writing requirements. After finishing the writing, check your content against these requirements one by one.

[Example]

The AudioRenderer class provides open audio playback capabilities. For details about the APIs, see the API reference.

Table 1 Audio playback APIs

How to Develop

[Writing Requirements]

Mandatory. Describe the overall process to help developers quickly complete the task. The table below describes the writing requirements. After finishing the writing, check your content against these requirements one by one.

[Example]

1. Use AudioStreamInfo.Builder to create an AudioStreamInfo instance for audio stream parameters. The following example uses the default values of the input parameters for AudioStreamInfo.Builder. You need to set the parameters based on the audio stream specification.

   AudioStreamInfo audioStreamInfo = new AudioStreamInfo.Builder().sampleRate(    AudioStreamInfo.SAMPLE_RATE_UNSPECIFIED)    .audioStreamFlag(AudioStreamInfo.AudioStreamFlag.AUDIO_STREAM_FLAG_NONE)    .encodingFormat(AudioStreamInfo.EncodingFormat.ENCODING_INVALID)    .channelMask(AudioStreamInfo.ChannelMask.CHANNEL_INVALID)    .streamUsage(AudioStreamInfo.StreamUsage.STREAM_USAGE_UNKNOWN)    .build();
   

   Example code for playing a PCM stream:

   AudioStreamInfo audioStreamInfo = new AudioStreamInfo.Builder().sampleRate(44100)// 44.1 kHz    .audioStreamFlag(AudioStreamInfo.AudioStreamFlag.AUDIO_STREAM_FLAG_MAY_DUCK)// Set audio ducking.    .encodingFormat(AudioStreamInfo.EncodingFormat.ENCODING_PCM_16BIT)//16-bit PCM    .channelMask(AudioStreamInfo.ChannelMask.CHANNEL_OUT_STEREO)// Set the dual output channel.    .streamUsage(AudioStreamInfo.StreamUsage.STREAM_USAGE_MEDIA)// Set the stream to be used for media.    .build();
   

2. Build the playback parameter structure via AudioRendererInfo for the audio stream created in Step 1, and use AudioRendererInfo.Builder to create an instance. The following example uses the default parameter values of the AudioRendererInfo.Builder instance. You need to set the playback parameters based on the audio playback specification.

   AudioRendererInfo audioRendererInfo = new AudioRendererInfo.Builder().audioStreamInfo(audioStreamInfo)    .audioStreamOutputFlag(AudioRendererInfo.AudioStreamOutputFlag.AUDIO_STREAM_OUTPUT_FLAG_NONE)    .bufferSizeInBytes(0)    .distributedDeviceId("")    .isOffload(false)    .sessionID(AudioRendererInfo.SESSION_ID_UNSPECIFIED)    .build();
   

   Example code for playing a PCM stream:

   AudioRendererInfo audioRendererInfo = new AudioRendererInfo.Builder().audioStreamInfo(audioStreamInfo)    .audioStreamOutputFlag(AudioRendererInfo.AudioStreamOutputFlag.AUDIO_STREAM_OUTPUT_FLAG_DIRECT_PCM)// Set direct PCM output    .bufferSizeInBytes(100)    .distributedDeviceId("E54***5E8")// Use distributed device E54***5E8 for playback.   .isOffload(false)//  Value false indicates that the audio stream is transmitted to the buffer on a segment-by-segment basis for several times and then played. Value true indicates that the audio stream is transmitted to the HAL layer at a time.    .build();
   

3. Specify the playback mode based on the audio stream to be played. The playback modes differ only in the data writing process. Create an AudioRenderer instance using a constructor that fits your need. ....

4. After the playback task is complete, call the release() method on the AudioRenderer instance to release resources.

(Optional) Commissioning and Verification

[Writing Requirements]

Optional. After the development is complete, perform commissioning and verification to ensure that the operation is successful. The operation procedure requirements are the same as those in Development Guidelines. Other specific writing requirements are as follows. After finishing the writing, check your content against these requirements one by one.

Development Example

[Writing Requirements]

Provide a complete sample, briefly describe the principle and implementation of the sample, and provide a link to the source code repository.

The following sample is provided to help you better understand how to xx:

• xxx (A link to the source code repository)

This sample xxx.